Reactions of tetrafluoroethylene oligomers. Part 2. Some reactions of 4,4,5,5,5-pentafluoro-3-pentafluoroethyl-3-trifluoromethylpentanoic acid (pentamer acid) and related compounds

Abstract

The acid R_fCH₂CO₂H (1)[R_f= CF₃(C₂F₅)₂C] derived from the tetrafluoroethylene pentamer (2) by base hydrolysis has been converted by Kolbe electrolysis into the dimer R_fCH₂CH₂R_f(3). The salt R_fCH₂CO₂Ag (4) with bromine afforded R_fCH₂Br (5) which was unreactive to nucleophiles under a variety of conditions. R_fCH₂COCl (6) with sodium azide under Curtius reaction conditions gave (R_fCH₂NH)₂CO (7), whereas reaction of (6) with trimethylsilyl azide or sodium azide–18-crown-6 gave R_fCH₂NCO (8). R_fCH₂NCO and cyclohexylamine gave R_fCH₂NHCONHC₆H₁₁(9). Neither urea, (7) or (9), could be hydrolysed. R_fCH₂COCl (6) reacted with ammonia to give R_fCH₂CONH₂(10) and with cyclohexylamine to yield R_fCH₂CONHC₆H₁₁(11). The amide (10) under Hofmann degradation conditions gave the urea (7). The acid (1) reacted with sodium azide in 25% oleum to yield R_fCH₂NH₃⁺ HSO₄^–(12) which, on reaction with dilute base, gave R_fCH₂NH₂(13). Reaction of R_fCH₂NH₃(13) or R_fCH₂NH₃⁺ HSO₄^–(12) with sodium nitrite afforded R_fCHN₂(14) as a stable liquid.